Video codec engines are whirring back into life, disturbed by recent HEVC Advance movements in Asia Pacific. Netflix sent out disruptive ripples of its own late last week by adding support for AV1 on Android smartphones in a move that will see adoption soar for the royalty-free, Google-backed compression technology.
Netflix has reported 20% compression efficiency gains over VP9 by replacing it with AV1, which you could criticize for underperforming considering AV1 has promised as much as 30% efficiency increases over current generation codecs VP9 and HEVC (H.265). However, AV1 decoding is 30% more complex than VP9 or AVC.
Only select Netflix titles are available to stream via the Data Saving feature that enables AV1 compression.
Netflix is simply reacting to demand. One-in-five developers plan to implement AV1 in 2020, according to Bitmovin’s third annual developer survey, while device manufacturers, browser vendors, and content distributers like Cisco, Mozilla, and YouTube have already started implementing AV1 on larger scales, so AV1 is well positioned to compete with H.265/HEVC and to succeed VP9 for open-source use cases in 2020.
Device makers and streaming providers now have a full toolset to start developing fully AV1 compliant products and services. The AV1 code base was finally frozen in March 2018, but it took until February 2019 for the first fully compliant encoder to arrive in the form of Intel’s first open source CPU-based encoder for AV1 – and even that is a software tool running in the CPU ahead of dedicated AV1 encoders which arrived later in 2019.
Netflix’s AV1 Android rollout follows on from its work with VP9, released as part of its mobile encodes in 2016 and further optimized with shot-based encodes in 2018. After deploying per-title encoding in 2015, this shot-based encoding framework, called Dynamic Optimizer, gave Netflix capabilities for more granular optimizations with a video stream.
We recall a study carried out at Moscow State University in early 2018, where AV1 was found to be between 2,500 and 3,000 times slower than competing codecs. However, AV1 backing group the Alliance for Open Media (AOMedia) claimed few months later, in conversation with Faultline, that Moscow State researchers actually used a 6-month old version of AV1 with no optimization tools, and the research team never contacted AOMedia.
“The code we produce is experimental, meaning the codec comes with different options, so you need to write the code through the lens of different bit streams and apply optimization afterwards. Moscow State University is doing some good work,” AOMedia’s Executive Director Gabe Frost, of Microsoft, explained to us in April 2018.
The elephant in the room however is when will Netflix AV1 support arrive on Apple devices? That is a convoluted situation, considering Apple is a substantial string-puller behind MPEG-LA, one of the HEVC patent pool groups, that publicly argued that the success of AV1 world cripple the video market by making the powerful even more powerful, shifting control from device makers to internet behemoths like Google. Of course, that is equally rich coming from an Apple-backed organization, with Apple also a member of AV1’s sponsorship group AOMedia.
For example, Apple’s Safari browser still does not support VP9, while YouTube itself does not support HEVC 4K streaming, meaning no YouTube 4K video streaming for Safari users.
“While our goal is to roll out AV1 on all of our platforms, we see a good fit for AV1’s compression efficiency in the mobile space where cellular networks can be unreliable, and our members have limited data plans,” according to a Netflix blog post.
Taking in the bigger picture, the MPEG/ITU camp has cause for concern, but this is not for technical reasons, but because of the deterioration in the licensing situation that coincided with the roll out of HEVC. This has always been a bugbear for the MPEG range, but was at least contained during the MPEG-2 and then AVC eras, while HEVC patents have fragmented into three pools, with another called Velos Media pitted against HEVC Advance and MPEG LA, presenting a confusing and risky picture for potential users. This has given oxygen to the AV1 movement far more than arguable and sometimes spurious claims of performance gains over HEVC.
“Our AV1 support on Android leverages the open-source dav1d decoder built by the VideoLAN, VLC, and FFmpeg communities and sponsored by AOMedia. Here we have optimized dav1d so that it can play Netflix content, which is 10-bit color. In the spirit of making AV1 widely available, we are sponsoring an open-source effort to optimize 10-bit performance further and make these gains available to all,” added Netflix.